Fixes #170 - implement usergroups

Added migration
Added tests
Added MVC files
Added the routes as well
Added the program logic and additional views
Added RESTful actions for update and create
Added validations to ensure that usergroup.name and user.login do not collide...

fixes #199 - Remove activescaffold from the puppetclasses page, search functionality will follow

reports controller test is stand-by. puppetclasses controller test finished.

Add support for multiple puppet classes per host / operating system / environment etc
this should enable a proper dropdowns when creating the gui part that shows possible puppet class / operating system / env combinations

fix external nodes to actully work with multiple puppet classes...